Retractable turning knob

Abstract: A control member or knob (M), of the push-pull type, to be associated with a control element provided on the control panel of an apparatus such as a household electrical appliance or an electrical apparatus in general, comprises an end part (13) to be connected to said panel and having a member (18) to receive and cooperate torsionally with said control element, with said part (13) there being associated a body (1) axially movable along said part against the action of a spring (9) and cooperating torsionally therewith. The member (18) cooperating with the control element is arranged, movable relative to the knob longitudinal axis (X), within a cavity (17) in the end part (13) of the knob (M); there being provided axial retention means (25, 31) for this latter which prevent said member (18) escaping from the cavity (17) while enabling it to undergo said movement.

Description: This invention relates to a control member or knob in accordance with the introduction to the main claim. EP-A-0 173 820 discloses a control member according to the preamble of claim 1. As is well known, the knob or control member, in particular of the push-pull type, of an apparatus such as a household electrical appliance, for example an oven or the like, is connected to a control element (in particular a control shaft having at least one flat face) on the control panel of the appliance. This connection is made during the final stages in the construction of the appliance by inserting the knob into a usual switch support associated with a front cover on the control panel and comprising an aperture which cooperates with a hole in said cover in order to receive the knob. This latter comprises, within a usual cavity in its end part or stem, an insert fixed to the cavity walls and provided with a hole of such shape as to receive the said control shaft and to cooperate torsionally with it. A knob having the aforesaid known characteristics allows proper use of the appliance, but has the drawback of not being always easy to connect to the control shaft during the construction of the appliance. In this respect, even small defects in the construction of the stem and of the insert within its cavity can result in an undesirable inclination of the axis of the hole in the insert (relative to the longitudinal axis of the knob) such that the said connection is totally impossible or is made very difficult to effect. In other words, because of imperfect alignment between the axis of the hole in the insert within the knob body and the axis of the control shaft, and because the knob is associated with the switch support in such a manner that the connection can be made only if this alignment exists, the insertion of said shaft into the insert in the stem is prevented or made very difficult. In this latter case the insertion can be achieved only by forcing, which can lead to the breakage of the insert and/or stem (these being generally of plastics construction), leading to obvious problems in using the appliance. An object of the present invention is to provide a knob for easy and reliable connection to a control shaft located on the control panel of an apparatus such as a household electrical appliance, a high fidelity system or a similar electrical apparatus. A particular object of the invention is to provide a knob which can be connected to the control shaft even if the knob stem (and hence the knob itself) and said shaft are misaligned. A further object is to provide a knob of reliable use and low construction cost. This and further objects which will be apparent to the expert of the art are attained by a control member or knob in accordance with the accompanying claims. The present invention will be more apparent from the accompanying drawings, which are provided by way of non-limiting example and in which: Figure 1 is a longitudinal section through a first embodiment of a push-pull knob according to the invention; Figure 2 is an exploded perspective partial view of a part of the knob of Figure 1; Figure 3 is a perspective view of a second embodiment of the invention; and Figure 4 is an exploded view of a part of the knob of Figure 3. With reference to Figures 1 and 2, a knob of push-pull type is indicated overall by M and comprises a tubular body 1 closed at its free end by an endpiece 2 and supporting at its other end 3 a usual hook or shoe 4 connected to the body 1 by a known elastic pin 5. The body 1 comprises an inner cavity 6 bounded by a portion 7 (internal to said cavity) positioned in proximity to said endpiece 2. On said portion 7 there rests the end 8 of a compression spring 9, the other end 10 of which acts on the inner part 11 of a socket-shaped end 12 of the end part or stem 13 of the knob M. The body 1 cooperates torsionally with the stem 13 and can move longitudinally (ie along an axis X) relative to this latter. This latter is of polygonal shape, a side 15 thereof comprising a usual labyrinth 16 for the shoe 4. According to the invention, the stem 13 is tubular and comprises a cavity containing an insert 18 independent of said part 13 and internally comprising a cavity 19 which opens into one end 20 of said stem. The cavity 19 comprises internally a flat spring 22 (of known use) and is of a usual shape enabling it to be torsionally coupled to a control shaft of an apparatus such as an electric oven (not shown). The insert 18 comprises in a side face 23 an oval arched-wall recess 24 able to cooperate with an oval projection 25 of slightly smaller dimensions than said recess and projecting from an inner wall 26 bounding the cavity 17 in the stem 13. When the insert 18 is positioned within the cavity 17, the projection 25 (which is preferably elastically deformable in the sense that it can undergo slight compression to enable the insert 18 to be inserted into the cavity 17) projects into the recess 24 to axially retain the insert within the end part 13 of the knob. At the same time, as the projection 25 is smaller than the recess 24, the engagement between these parts allows the insert 18 to undergo movement along a plurality of planes containing the knob longitudinal axis X. In other words, the insert 18 is able to move within the cavity 17 such that the longitudinal axis Y of the cavity 19 and hence of the insert 18 (generally coaxial with the axis X) can assume any inclination to the longitudinal axis of the knob. In this manner, when connecting this latter to a control shaft of the control panel of an apparatus such as a household electrical appliance, even if the knob and the shaft are not perfectly coaxial this latter can still be inserted into the cavity 19 and be torsionally coupled to the knob, because of the possible different orientation of the axis Y of the insert 18 relative to the axis X of the knob (and of the cavity 17 which it contains). Figures 3 and 4 show a modification of the invention. In these figures, in which parts corresponding to those of the already described figures are indicated by the same reference numerals, the insert 18 comprises a transverse through hole 30 (in place of the recess 24) perpendicular to the axis Y of the insert 18 and arranged to cooperate with a pin 31. This latter cooperates with elongate through slots 35 provided in the opposing sides 32 and 33 of the end part 13 of the knob M. In the illustrated embodiment the insert 18 is inserted into the cavity 17 of the part 13 and when the hole 30 and the slots 35 are aligned, the insert is retained within this cavity by inserting the pin 31 through said hole and slots. Said pin is locked in position in known manner so as not to escape from the hole 30. The cooperation between the pin (or rather its ends 31A projecting from the hole 30) and the slots 35 defines a sort of hinge about which the insert 18 is able to rotate and hence assume positions in which its longitudinal axis (shown coaxial to the axis X in the figures) is inclined to the longitudinal axis of the part 13 and hence of the knob M. In this manner the control shaft on the control panel can in any event be inserted into the hole 19 in the insert 18, so that rotating the knob M results in rotation of the shaft and hence activation and/or adjustment of the operation of the household electrical appliance.

Claims: A control member or knob of push-pull type able to cooperate with a control element on a control panel of an apparatus such as a household electrical appliance or an electrical apparatus, said knob comprising an end part (13) with a retention member (18) able to receive and cooperate torsionally with said control element, said end part cooperating with a body (1) movable axially along said end part and along the longitudinal axis (X) of the knob against the action of a spring (9) and cooperating torsionally with said end part, characterised in that said retention member (18) is positioned movable with respect to said longitudinal axis (X) within a cavity (17) provided in said end part (13); and axial retention means (24, 25; 30, 31, 35) are provided such to prevent said retention member (18) escaping from said cavity but are able to allow movement of said retention member relative to said end part. A control member as claimed in claim 1, characterised in that said retention means (24, 25) include a projection (25) with at least one curved portion projecting from an inner wall (26) which bounds said cavity (17), said projection cooperates with a recess (24) provided in a side face (23) of said retention member (18), and said recess has larger dimensions than said projection. A control member as claimed in claim 2, characterised in that said recess (24) is an arched-wall recess. A control member as claimed in claim 1, characterised in that said retention means (30, 31, 35) include a pin (31) stably inserted in a transverse through hole (30) provided in said retention member (18), said hole is perpendicular to the longitudinal axis (Y) of said retention member, said pin (31) cooperates with elongate through slots (35) provided in opposing side walls (32, 33) of said end part (13), and the ends (31A) of said pin projecting from said transverse through hole define with said through slots a hinge about which said retention member can rotate within said cavity (17).

Inventors: CUOCO VINCENZO, GIMELLI ELIO, PORRINI MASSIMO, VENTURINI SILVANO, CUOCO, VINCENZO, GIMELLI, ELIO, PORRINI, MASSIMO, VENTURINI, SILVANO, CUOCO, VINCENZO, C/O WHIRLPOOL ITALIA S.R.L., GIMELLI, ELIO, C/O WHIRLPOOL ITALIA S.R.L., PORRINI, MASSIMO, C/O WHIRLPOOL ITALIA S.R.L., VENTURINI, SILVANO, C/O WHIRLPOOL ITALIA S.R.L.
Applicants: WHIRLPOOL EUROP, WHIRLPOOL EUROPE B.V.
Application year: 1994
Main classification: G05G1
IPC codes: H01H13, G05G1